216 research outputs found
Bounds on R-parity violating SUSY Yukawa couplings from semileptonic decays of baryons
We consider tree-level corrections to hypercharge changing semileptonic
decays of certain baryons induced by a minimal supersymmetric standard model
with explicitly broken R-parity via -violation. This study leads to a new
set of constraints on the products of couplings arising from the LQd
operator of the superpotential.Comment: Latex (8 pages), no figur
R-Parity Violation and Peccei-Quinn Symmetry in GUTS
We address the question whether it is possible in GUTs to obtain R-parity
violation with a large hierarchy of strengths so that
the proton is stable while phenomenologically interesting -violation is
present. We consider versions of SU(5) with a built-in Peccei-Quinn symmetry
spontaneously broken at an intermediate scale. The P-Q symmetry and the field
content guarantee a large suppression of the effective -violating terms by a
factor while the effective -violating terms stay
large.Comment: 8 pages, no figure
N=1 effective potential from dual type-IIA D6/O6 orientifolds with general fluxes
We consider N=1 compactifications of the type-IIA theory on the T6/(Z2xZ2)
orbifold and O6 orientifold, in the presence of D6-branes and general NSNS, RR
and Scherk-Schwarz geometrical fluxes. Introducing a suitable dual formulation
of the theory, we derive and solve the Bianchi identities, and show how certain
combinations of fluxes can relax the constraints on D6-brane configurations
coming from the cancellation of RR tadpoles. We then compute, via generalized
dimensional reduction, the N=1, D=4 effective potential for the seven main
moduli, and comment on the relation with truncated N=4 gaugings. As a
byproduct, we obtain a general geometrical expression for the superpotential.
We finally identify a family of fluxes, compatible with all Bianchi identities,
that perturbatively stabilize all seven moduli in supersymmetric AdS4.Comment: 19 pages, no figures, JHEP3 LaTeX. Published versio
Report of the Beyond the MSSM Subgroup for the Tevatron Run II SUSY/Higgs Workshop
There are many low-energy models of supersymmetry breaking parameters which
are motivated by theoretical and experimental considerations. Here, we discuss
some of the lesser-known theories of low-energy supersymmetry, and outline
their phenomenological consequences. In some cases, these theories have more
gauge symmetry or particle content than the Minimal Supersymmetric Standard
Model. In other cases, the parameters of the Lagrangian are unusual compared to
commonly accepted norms (e.g., Wino LSP, heavy gluino LSP, light gluino, etc.).
The phenomenology of supersymmetry varies greatly between the different models.
Correspondingly, particular aspects of the detectors assume greater or lesser
importance. Detection of supersymmetry and the determination of all parameters
may well depend upon having the widest possible view of supersymmetry
phenomenology.Comment: 78 pages, 49 figures, to appear in the Proceedings of the Tevatron
Run II SUSY/Higgs Workshop. Editor: J. F. Gunion; BTMSSM Convenors: M.
Chertok, H. Dreiner, G. Landsberg, J. F. Gunion, J.D. Well
New LEP bounds on -violating scalar couplings: R-parity violating supersymmetry or diquarks
We use the precision electroweak data at LEP to place bounds on -violating
Yukawa couplings, two theoretically appealing examples being provided by
-parity--violating supersymmetry and diquarks. The couplings involving the
third generation quarks are most severely constrained. These bounds are
complementary to those obtained from low-energy processes.Comment: LaTeX, 12 pages, 4 figures (uuencoded compressed postscript files
added through "figures" option
R-parity violating resonant stop production at the Large Hadron Collider
We have investigated the resonant production of a stop at the Large Hadron
Collider, driven by baryon number violating interactions in supersymmetry. We
work in the framework of minimal supergravity models with the lightest
neutralino being the lightest supersymmetric particle which decays within the
detector. We look at various dilepton and trilepton final states, with or
without b-tags. A detailed background simulation is performed, and all possible
decay modes of the lighter stop are taken into account. We find that higher
stop masses are sometimes easier to probe, through the decay of the stop into
the third or fourth neutralino and their subsequent cascades. We also comment
on the detectability of such signals during the 7 TeV run, where, as expected,
only relatively light stops can be probed. Our conclusion is that the resonant
process may be probed, at both 10 and 14 TeV, with the R-parity violating
coupling {\lambda}"_{312} as low as 0.05, for a stop mass of about 1 TeV. The
possibility of distinguishing between resonant stop production and
pair-production is also discussed.Comment: 20 pages, 4 figures, 6 tables; Version accepted by JHE
Z' Decays into Four Fermions
If a new is discovered with a mass at LHC/SSC, its (rare)
decays into two charged leptons plus missing transverse energy will probe the
coupling to the lepton doublet and to , allowing
further discrimination among extended electroweak models.Comment: 9 pages plus 1 figure (not included but available), UG-FT-22/9
Single top quark production as a probe of R-parity-violating SUSY at pp and p\bar p colliders
We investigate the ability of single top quark production via qq'->
squark->tb and q \bar q'->slepton->t\bar b at the LHC and Tevatron to probe the
strength of R-parity violating couplings in the minimal supersymmetric model.
We found that given the existing bounds on R-parity violating couplings, single
top quark production may be greatly enhanced over that predicted by the
standard model, and that both colliders can either discover R-parity violating
SUSY or set strong constraints on the relevant R-parity violating couplings. We
further found that the LHC is much more powerful than the Tevatron in probing
the squark couplings, but the two colliders have comparable sensitivity for the
slepton couplings.Comment: 15 pages, 4 figure
MSSM in view of PAMELA and Fermi-LAT
We take the MSSM as a complete theory of low energy phenomena, including
neutrino masses and mixings. This immediately implies that the gravitino is the
only possible dark matter candidate. We study the implications of the
astrophysical experiments such as PAMELA and Fermi-LAT, on this scenario. The
theory can account for both the realistic neutrino masses and mixings, and the
PAMELA data as long as the slepton masses lie in the TeV range. The
squarks can be either light or heavy, depending on their contribution to
radiative neutrino masses. On the other hand, the Fermi-LAT data imply heavy
superpartners, all out of LHC reach, simply on the grounds of the energy scale
involved, for the gravitino must weigh more than 2 TeV. The perturbativity of
the theory also implies an upper bound on its mass, approximately TeV.Comment: Published version, figures update
The Neutron Electric Dipole Moment and CP-violating Couplings in the Supersymmetric Standard Model without R-parity
We analyze the neutron electric dipole moment (EDM) in the Minimal
Supersymmetric Model with explicit R-parity violating terms. The leading
contribution to the EDM occurs at the 2-loop level and is dominated by the
chromoelectric dipole moments of quarks, assuming there is no tree-level
mixings between sleptons and Higgs bosons or between leptons and gauginos.
Based on the experimental constraint on the neutron EDM, we set limits on the
imaginary parts of complex couplings and
due to the virtual b-loop or tau-loop.Comment: final manuscript to appear in Phys. Rev. D, 15 pages, latex, 4
figures include
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